1. Field of the Invention
The invention relates to the field of agricultural machinery, more particularly that of mowers.
2. Discussion of the Background
Mowers are known from several documents, especially patents EP 839 443, EP 809 928 or FR 2 635 433 in the name of the Applicant Company. These machines are fixed to the lift system of a tractor using a supporting structure with a three-point hitching frame for coupling.
In the transport configuration, the cutter bar is folded behind the tractor in order to occupy a minimum amount of space to allow the vehicle to move around on the road network.
In the work configuration, the cutter bar is deployed to the side of the tractor so as to mow the plants.
For reasons of maximum productivity, the use of bars supporting a great many cutting tools is desirable, that is to say a cutter bar that is as long as is technically feasible.
With long cutter bars, the problem of the size of the mower in transport configuration arises.
In an attempt to solve this problem, cutter bars that can be folded backwards have been proposed. This solution is suited to machines with cutter bars of medium size, but not for machines that have very long bars, because their center of gravity becomes so far away from the tractor.
For longer cutter bars, folding the bar upwards, vertically, has proved to be an attractive solution, although here again, the permissible size for transport has proved limiting and new solutions have been investigated.
Recently, patent DE 195 34 695 has proposed folding the cutter bar beyond the vertical, at an angle of 105° to 150°, this configuration allowing the cutting tool to be positioned diagonally with respect to the tractor and therefore allowing use of a longer cutter bar. In order to achieve this configuration, the machine described has two single-acting hydraulic jacks, one of them moving the bar into the vertical position and the other moving it beyond this position, slowing its descent.
The use of two single-acting jacks between the supporting structure and the cutter bar entails a bearing frame and a complex arrangement of jacks in order to effect the various movements of the cutter bar with the protector; this solution is expensive and not very functional.
The articulations that allow the cutter bar of mowers to be unfolded and folded additionally present safety problems in the various operating configurations. For example, it is desirable for the work configuration, that is to say when the cutting tools are activated, to be able to be moved away from the horizontal position quickly, in order to avoid an obstacle or to maneuver the tractor, for example, without the need to activate the transport configuration. In this so-called maneuvering configuration, safety measures need to be in place to prevent unwanted movements of the cutter bar.
There is therefore a problem as regards the functionality and the folding—unfolding of the cutter bar using articulations that are inexpensive but have the safety measures in place that are necessary for all the configurations: transport, work or maneuvering.